Wireless charging device, a receiver device, and a method of operating the same

1. A wireless charging device comprising: a driver unit capable of generating an alternating current (AC) voltage signal having a first frequency of a first frequency standard, wherein the driver unit is also capable of generating the AC voltage signal having a second frequency of a second frequency standard; a transmitting unit coupled to the driver unit and configured to transmit the AC voltage signal as wireless power to a receiver device; and a control unit configured to: detect a change in voltage or impedance while the driver unit is generating the AC voltage signal, detect a presence of the receiver device based on the change being greater than a threshold value for a predefined time period, confirm the presence of the receiver device based on the change in the voltage or impedance at least once in a predetermined time interval following a previous confirmation, wherein a duration of the predetermined time interval is greater than a duration of the predefined time period, determine that the receiver device is configured for a particular one of the first frequency standard or the second frequency standard based the change occurring while the driver unit is generating the AC voltage signal having the first frequency or the second frequency, respectively, cause the driver unit and the transmitting unit to transmit the AC voltage signal having the first frequency when the receiver device is configured for the first frequency standard, and cause the driver unit and the transmitting unit to transmit the AC voltage signal having the second frequency when the receiver device is configured for the second frequency standard.

2. The wireless charging device of claim 1, further comprising: circuitry configured to measure the change in impedance or voltage at the transmitting unit, wherein the change in impedance or voltage is caused by the receiver device at regular intervals to confirm the presence of the receiver device.

3. The wireless charging device of claim 2, wherein the driver unit is configured to continuously transmit the AC voltage signal to the receiver device while the presence of the receiver device is confirmed.

4. The wireless charging device of claim 1, wherein the control unit is configured to: distinguish between the receiver device and a foreign object based on detecting the foreign object when the change occurs for more time than the predefined time period, and control the driver unit to stop transmitting the AC voltage signal when the foreign object is detected.

5. The wireless charging device of claim 1, wherein the control unit is configured to: cause the driver unit and transmitting unit to repeatedly alternate between the first frequency and the second frequency during respective first and second time periods until detecting the receiver device operating at the first frequency or the second frequency; determine whether the receiver device is proximate to the transmitting unit and configured for the first frequency standard based on a change in a first voltage associated with the AC voltage signal during the first time period when the driver unit is generating the AC voltage signal having the first frequency; and determine whether the receiver device is proximate to the transmitting unit and configured for the second frequency standard based on a change in a second voltage associated with the AC voltage signal during the second time period when the driver unit is generating the AC voltage signal having the second frequency.

6. The wireless charging device of claim 5, wherein the control unit is configured to: detect the receiver device configured for the first frequency standard when the change in the first voltage is greater than a first threshold value; and detect the receiver device configured for the second frequency standard when the change in the second voltage is greater than a second threshold value.

7. A method for wireless power transfer, comprising: generating, by a driver unit, an alternating current (AC) voltage signal, wherein the driver unit is capable of generating the AC voltage signal having a first frequency within a first frequency range of a first frequency standard, and wherein the driver unit is also capable of generating the AC voltage signal having a second frequency within a second frequency range of a second frequency standard; detecting a change in voltage or impedance while the driver unit is generating the AC voltage signal; detecting a presence of a receiver device based on the change being greater than a threshold value for a predefined time period; confirming the presence of the receiver device based on the change in the voltage or impedance at least once in a predetermined time interval following a previous confirmation, wherein a duration of the predetermined time interval is greater than a duration of the predefined time period; determining that the receiver device is configured for a particular one of the first frequency standard or the second frequency standard based on the change occurring while the driver unit is generating the AC voltage signal having the first frequency or the second frequency, respectively; causing a transmitting unit and the driver unit to transmit the AC voltage signal having the first frequency when the receiver device is configured for the first frequency standard; and causing the transmitting unit and the driver unit to transmit the AC voltage signal having the second frequency when the receiver device is configured for the second frequency standard.

8. The method of claim 7, further comprising: measuring the change in impedance or voltage at the transmitting unit, wherein the change in impedance or voltage is caused by the receiver device at regular intervals to confirm the presence of the receiver device.

9. The method of claim 7, further comprising: distinguishing between the receiver device and a foreign object based on detecting the foreign object when the change occurs for more time than the predefined time period; and stopping transmission of the AC voltage signal when the foreign object is detected.

10. The method of claim 7, further comprising: causing the driver unit and transmitting unit to repeatedly alternate between the first frequency and the second frequency during respective first and second time periods until detecting the receiver device operating at the first frequency or the second frequency; determining whether the receiver device is proximate to the transmitting unit and configured for the first frequency standard based on a change in a first voltage associated with the AC voltage signal during the first time period when the driver unit is generating the AC voltage signal having the first frequency; and determining whether the receiver device is proximate to the transmitting unit and configured for the second frequency standard based on a change in a second voltage associated with the AC voltage signal during the second time period when the driver unit is generating the AC voltage signal having the second frequency.

11. The method of claim 10, further comprising: detecting the receiver device configured for the first frequency standard when the change in the first voltage is greater than a first threshold value; and detecting the receiver device configured for the second frequency standard when the change in the second voltage is greater than a second threshold value.

12. A wireless charging device comprising: a driver unit capable of generating one of a first alternating current (AC) voltage signal having a first frequency of a first frequency standard and a second alternating current (AC) voltage signal having a second frequency of a second frequency standard; a transmitting unit coupled to the driver unit and configured to selectively transmit the first AC voltage signal having the first frequency or the second AC voltage signal having the second frequency; a detector to detect a change in voltage or impedance while the driver unit is generating the first AC voltage signal or the second AC voltage signal; and a control unit coupled to the transmitting unit and the driver unit, the control unit configured to: detect a presence of a first receiver device or a second receiver device based on the change in the voltage or the impedance being greater than a threshold value for a predefined time period while the driver unit is generating the first AC voltage signal having the first frequency or the second AC voltage signal having the second frequency; detect the first receiver device of the first frequency standard based on first confirmation signaling from the first receiver device; and detect the second receiver device of the second frequency standard based on second confirmation signaling from the second receiver device and confirm the presence of the first receiver device based on the change in the voltage or impedance at least once in a predetermined time interval following a previous confirmation, wherein a duration of the predetermined time interval is greater than a duration of the predefined time period.

13. The wireless charging device of claim 12, wherein the control unit is configured to: generate a first control signal in response to detecting the first receiver device, wherein the first control signal is configured to cause the driver unit to generate the first AC voltage signal having the first frequency; and generate a second control signal in response to detecting the second receiver device, wherein the second control signal is configured to cause the driver unit to generate the second AC voltage signal having the second frequency.

14. The wireless charging device of claim 12, wherein the control unit is configured to: detect the first receiver device configured for the first frequency standard based on a change in a first voltage measured at a first junction between a first coil of the transmitting unit and a first capacitor, wherein the change in the first voltage is compared with a first threshold value; and detect the second receiver device configured for the second frequency standard based on a change in a second voltage measured at a second junction between a second coil of the transmitting unit and a second capacitor, wherein the change in the second voltage is compared with a second threshold value.

15. The wireless charging device of claim 12, wherein the transmitting unit includes a first coil configured to transmit the first AC voltage signal having the first frequency and a second coil configured to transmit the second AC voltage signal having the second frequency.